The composting apparatus disclosed herein relates to improvements in apparatus of the type disclosed in Cobey U.S. Pat. No. 3,369,797; Urbanczyk U.S. Pat. No. 4,019,723; Chance U.S. Pat. No. 4,199,030; Jenison U.S. Pat. No. 4,360,065 and Slater U.S. Pat. No. 5,001,894.
Compost turning and windrow forming machines generally incorporate a rotating drum having radially projecting teeth with flat or slightly curved throwing surfaces for turning organic matter deposited in piles. Turning the organic matter increases the rate of oxidation and bacterial action which is generally required during the transformation of yard waste, manure from poultry and cattle feed lots, sludge from sewage treatment plants, rubbish and other organic waste material during the composting process.
Cobey U.S. Pat. No. 3,369,797 discloses a mobile apparatus for straddling ground-deposited material which is provided with a power-driven rotatable drum having a plurality of radially projecting narrow teeth which engage and fragment the material. The teeth are disclosed as being positioned in a helical or spiral pattern in converging relationship from each end of the drum toward its midpoint where congestion occurs. Throwing surfaces on the teeth are parallel to the direction of the spiral pattern and angularly inclined to the direction of travel of the periphery of the drum and in a converging relationship towards the midpoint of the drum. The configuration of the underside of the frame above the drum provides a funnel effect for the discharge of the material that is thrown in an upward and rearward direction.
The teeth are spaced apart a distance which is several times the width of each tooth, leaving wide spaces between the teeth. The auger effect of the spaced teeth having faces parallel to the spiral pattern is augmented by a pair of broad-surfaced blades mounted near the center of the drum.
Chance U.S. Pat. No. 4,199,030 discloses a rotatable plowing tool, for farming row crops, having a cylindrical rim and an array of soil digging teeth secured to the rim and projecting radially, each tooth of the array being rigidly secured to the rim with its radial axis disposed perpendicular to the axis of rotation of the rim and being characterized by first and second planar faces at least one of which is obliquely inclined with respect to the radial axis of the tooth and sloping away from the direction of rotation of the rim. The rim and drive wheels of the towing vehicle rotate in the same direction such that cultivated soil moves under the rim. The planar faces of each tooth converge at the distal end of the tooth to define a sharp cutting edge. Each tooth of the array on each rim is oriented in such a manner that the plane containing the cutting edge and the radial axis of the tooth defines an oblique cutting angle with respect to the plane containing the radial axis of the tooth and the line of travel of the carriage assembly. The soil engaged by the blades is moved laterally with respect to the line of travel to form elevated seed bed rows.
Jenison U.S. Pat. No. 4,360,065 discloses a cultivator adapted to straddle a windrow of material such as compost, equipped with a horizontal drum having a plurality of cultivator blades disposed in two helical arrays between opposite ends of the drum. Faces on the blades are parallel to the direction of travel of the machine and perpendicular to the longitudinal axis of the drum. The arrays are described as being circumferentially spaced 180.degree. apart about the drum and extending equal distances on opposite sides of the central, longitudinal, vertical plane along the center of the frame of the cultivator. The blades on the right and left sides of the drum have paddle portions at their ends transversely offset toward the central vertical plane and contoured to move material sideways and heap it up into a peak along the center of the windrow. The helical arrays of blades are identical and symmetrical on opposite sides of the windrow center, enabling repeated passes of the cultivator to circulate material between the inside and the outside of the windrow while maintaining it with a triangular cross section. Two specific blade shapes are disclosed, one primarily for windrow cultivation and aeration, and another for shredding paper, cardboard, magazines and the like prior to composting.
Slater U.S. Pat. No. 5,001,894 discloses a bearing guard for a compost turner adapted for guarding the bearing of a rotating mandrel from entanglement with polymeric bags used to haul leaves, grass clippings and the like to a landfill site. A cylindrical mandrel has a multiplicity of narrow turning tines extending generally perpendicularly from its cylindrical surface and the tines are arranged in two spiraling rows around the perimeter of the surface. The tines, having faces parallel to the direction of travel of the machine and perpendicular to the longitudinal axis of the drum, are oriented to urge compost toward the longitudinal central plane of the mandrel.
The configuration of teeth on rotating drums of composting apparatus heretofore devised were arranged in a helical spiral arrangement in an effort to form an auger configuration for moving material laterally. Some configurations require successive passes to complete the circulation of the material. However, a need exists for composting apparatus which more effectively mixes, turns and aerates material for speeding the decomposition of organic material in a manner that consumes less energy.